textproduct: Quad Cities

KEY MESSAGES

- Extreme Heat Warning continues through Thursday evening for much of the area with ongoing prolonged period of hot and very humid conditions. Daily peak heat index values of 100 to 105 and nighttime low temperatures only dropping into the mid to upper 70s.

- Humid conditions will continue into the holiday weekend. Cloud cover and slowly increasing storm chances will help to lower ambient temperatures. Storm chances will increase from the west and north into the weekend. Some storms may be strong to severe as well as have the potential to produce locally heavy rainfall.

SHORT TERM /THROUGH THURSDAY/

Issued at 213 PM CDT Wed Jul 1 2026

First, no changes to the current headlines. There is 20-33 percent probability that the heat headlines south of I-80 may need to get extended into Friday. How convection evolves over the next 24 hours will determine what will need to be done with the heat headlines across the area.

The 18z soundings has a weaker cap compared to previous days. However, there is still inhibition that needs to be overcome. Radar, however, shows weak cells developing north of Highway 30 in spite of the inhibition. Thus some isolated cells will be possible through sunset.

After sunset, the LLJ will increase with storms initiating in the LLJ and the edge of the EML. Some isolated convective cells will likely be seen north of Highway 30 during the evening. The bigger push will be after midnight when outflow boundaries from the storms in Minnesota/Wisconsin initiate additional storms in the Highway 20 corridor and possibly as far south as Highway 30.

Most storms will be below severe limits overnight but the high moisture levels in the atmosphere means locally heavy rain is a given. Precip loading in downdrafts could result in an isolated severe downburst from the stronger storms.

Some of the very short term models suggest the outflow boundary from the nocturnal convection getting as far south as I-80. Due to the overall weak forcing, the CAMs are having difficulty in developing rain that far south prior to sunrise.

By sunrise the LLJ will be in a weakening phase. Lingering convection will be mainly Highway 30 on north that will dissipate through mid-morning. Boundaries left over from the nocturnal convection will then be the foci for diurnal development Thursday afternoon.

Cloud cover from the morning convection will help suppress temperatures north of Highway 30 and should keep heat indices in the 95 to 100 range. South of Highway 30 heat indices are still expected to be over 100.

LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/

Issued at 240 AM CDT Wed Jul 1 2026

Thursday night an organized storm complex will arrive from the Plains. Damaging winds, heavy rainfall, and possibly some hail would be the main concerns.

Friday through Tuesday...Boundaries and cloud cover left over from the Thursday night storms will help to hold down temperatures and also provide boundaries for diurnal convection Friday afternoon that will continue into Friday night.

Starting Friday, rain chances will increase to 30-50% but not all areas will see rain.

Saturday through Wednesday Assessment...a certainty (>95%) that humid conditions will continue. Low (20-30%) confidence on storm timing and areal coverage.

Another disturbance moving through the Midwest Saturday and Saturday night currently looks to have the better chances to produce rain. This may or may not be in the form of an organized storm complex. Right now, the model consensus has rain chances at 30-55% with the better chances along/north of I-80.

Starting Sunday, there are additional upper level disturbances/waves progged to move through the area each day. However, there are timing differences. The main message is that while there are rain chances for each day, not everyone will see rain. Additionally, areal coverage of any precip is low at 15 to 25 percent.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 655 PM CDT Wed Jul 1 2026

VFR conditions are expected at all sites through 06 UTC with mostly clear skies and gusty southerly winds subsiding once the sun sets. After midnight, scattered thunderstorms are forecasted to move in around the Highway 20 corridor and could impact KCID (30% chance) and KDBQ (60% chance) with MVFR ceilings and visibility between 08 to 12 UTC. In the heaviest thunderstorms, conditions could briefly deteriorate to IFR, but this is currently unlikely (10-20%). A gust front with storms may also lead to variable winds for a couple hours before returning to southerly flow. In addition, a 30-35 knot LLJ is expected to move in after 06 UTC and persist through 12-13 UTC, providing southwesterly LLWS for a few hours at each site. Once these storms clear KCID and KDBQ by 12 UTC, VFR conditions return for the remaining TAF period.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Extreme Heat Warning until 10 PM CDT this evening for IAZ040>042-051>054. Extreme Heat Warning until 10 PM CDT Thursday for IAZ063>068- 076>078-087>089-098-099. IL...Extreme Heat Warning until 10 PM CDT this evening for ILZ001- 002-007. Extreme Heat Warning until 10 PM CDT Thursday for ILZ009- 015>018-024>026-034-035. MO...Extreme Heat Warning until 10 PM CDT Thursday for MOZ009-010.